a. An erroneous perception of reality: Mirrors gave the illusion of spaciousness.
b. An erroneous concept or belief: The notion that money can buy happiness is an illusion.
2. The condition of being deceived by a false perception or belief: spent months flailing about in illusion.
3. Something that is erroneously perceived or construed: The animal in the shadows turned out to be an illusion.
4. A fine transparent net fabric, used for dresses or trimmings.
[Middle English illusioun, from Old French, from Late Latin illūsiō, illūsiōn-, from Latin, a mocking, irony, from illūsus, past participle of illūdere, to mock : in-, against; see IN-2 + lūdere, to play; see leid- in the Appendix of Indo-European roots.]
il·lusion·al, il·lusion·ar′y (-zhə-nĕr′ē) adj.
(click for a larger image)illusion
top: straight horizontal rules appear curved
bottom: a gray box against a black background appears lighter than the same gray box against a white background
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.